1. Field of Invention
The invention concerns a tubing set for a medical liquid delivery device comprising a gate for the connection of vials containing drugs, in particular a tubing set intended to be used with hemodialysis machines. The invention further concerns a method for delivering drugs by means of the tubing set.
2. Description of the Prior Art
Most of the recent hemodialysis machines, are arranged also for carrying out another treatment, called hemofiltration. Hemofiltration is a renal replacement therapy which is used almost exclusively for acute renal failure. During hemofiltration, a patient's blood is passed through a filter where waste products and water are removed. Due to the water removal, a substitution liquid is needed in addition to the blood which is returned to the patient. Hemofiltration is sometimes used in combination with hemodialysis, originating the so called hemodiafiltration treatment.
In view of the above, recent hemodialysis machines, are provided with a specific circuit intended to deliver the substitution liquid.
In the following, for ease of description, reference will be made mainly to hemodialysis, however hemofiltration and hemodiafiltration should also be considered within the scope of the present invention.
In hemodialysis treatments which require an extracorporeal circulation it is often necessary to administer different drugs or therapeutic substances to the patient. The presence of the tubing set advantageously makes it possible to avoid the administering of the drug taking place through puncture carried out directly on the patient himself.
During the hemodialysis treatments it often becomes necessary to administer different drugs or therapeutic substances, like for example iron, heparin, erythropoietin, vitamins and antibiotics. The infusion of such substances in the extracorporeal circuit is currently carried out through conventional syringes or Pre-Filled Syringes (PFS). The substance is drawn from the vial or ampoule in which it is supplied by the producer and is then injected into a special puncturable cap provided along the tubing set. Thus there is a double transfer of the substance: firstly from the vial to the syringe and then from the syringe to the circuit.
Such an operation therefore requires the use of disposable materials, such as the syringe and the respective needle, just to transfer the substance from the vial to the tubing set. Moreover, such operation entails the risk for the service staff to be pricked by the syringe needle or injured by glass fragments originated during snapping off the ampoule neck.
Additionally, glass debris could fall into the ampoule and be delivered in the blood.
Furthermore, each transfer step entails a risk of contamination for the drug to be delivered, e.g. the risk of an accidental multiple use of a syringe.
Finally, some of the quoted substances need to be administered slowly, over a few minutes. From this it can easily be understood how the administering of various substances to more than one patient represents a considerable workload for the nursing staff responsible for the treatment.
WO 87/07159 discloses a medical liquid administration set which is intended for infusions related to an intravenous therapy; such set is not suitable for use in co-operation with a hemodialysis machine.
European patent application No. 09175001.8, filed by the same applicant, discloses a tubing set comprising a vial gate similar to the one set forth in the preamble of claim 1. However, according to that solution, the top end of the vent lumen should be preferably long enough to reach the air reservoir in the upside-down vial. Accordingly, that vial gate is suitable for cooperation with vials of one size only, due to the length of the vent spike. Moreover a long spike entails some problem for its manufacturing and entails some risks during its handling.